1. Field of the Invention
This invention relates to a rigging system for line array speakers. In particular, the invention relates to a system of assembling and suspending a plurality of line array speakers and adjusting the splay angle between the speakers to control and produce the desired sound radiation.
2. Related Art
A line array is a group of often similarly sized speakers positioned adjacent to one another to optimize sound level output over a larger coverage area. Line array speaker systems are often used in large venues, such as auditoriums and concert halls, where it is desirable to reproduce a high sound level across a wide coverage area. Line array speakers provide increased directivity at various frequencies. Providing increased directivity at various frequencies extends the near-field coverage area because the coverage distance from the near field to the far field transition zone is increased with frequency. The ability of line array speaker systems to increase near field extension is well known in the art. For this reason, line arrays offer significant advantages over traditional multi-box sound systems and are preferred for use in large venues.
To achieve an optimal sound level over a desired coverage area, line arrays are strategically positioned in various places, at varying heights and angles, throughout a venue. The positioning of the line arrays is determined by using simple equations that anticipate the performance of differently sized speakers based upon their arrangement relative to one another. The specific height of a line array and angle and spacing between the speakers in the line array are the main variables that govern the sound level output and coverage area of the line array. The height of an array governs the line array's directivity. The spacing of the individual speakers, which is a second-order effect, determines the lobing structure of the line array. For example, a relatively straight array may radiate the sound level desired for far field coverage. For near field coverage, the line arrays often require some degree of curvature to provide uniformity of coverage over a wider vertical angle.
Once the optimal speaker arrangement for a given venue is determined, the speakers in the line arrays are then typically arranged and mounted on specially designed racks. Depending upon the desired arrangement, the line arrays are then suspended in the air with hanging equipment and/or placed on the ground. By properly arranging the line array speakers and articulating or curving the line array in the vertical plane at a specific angle, one can provide excellent coverage for listeners seated in both the near and the far fields.
Despite the advantages that line arrays can provide over traditional multi-box sound systems, there are notable disadvantages with the known line array based systems. With conventional systems, it has been difficult to adjust and maintain the splay angle between adjacent speakers. Maintaining the angles between the line array speakers, and thereby the overall curvature of the line array system, is important to the performance of the sound system. This is especially true when the line arrays are configured for large venues having more than one seating plane. With the presence of more than one seating plane, curvature becomes very important to providing uniformity of coverage and the line arrays are often suspended in the air. Depending on the particular seating arrangement, the speakers must be deployed precisely and maintained at specific vertical angles to avoid phase interference between the sounds from the adjacent loudspeakers. With the current line array systems, it has been difficult to maintain the overall integrity of the line array once suspended in the air. The conventional systems are not truly ‘rigid’ in that the specific angles between the speakers cannot be maintained constant when the system is suspended or otherwise manipulated.
Another problem associated with the current line array systems is the difficulty of assembling, suspending and adjusting the plurality of loudspeakers in an array to the desired configuration. Presently, substantial, elaborate preparation and labor are required to assemble and install line array systems. The installation time and cost become significant, especially in large-scale operations, which can require many line arrays.
Another disadvantage of the conventional systems relates to the transportation of the line array systems from one location to another. The dimensions of the line array system play a significant role in determining the number of transportation vehicles needed, and consequently has a significant impact on transportation and operation costs. Many conventional sound systems utilize loudspeakers with associated frames that are more than 48 inches wide. Thus, it is impossible to vertically double stack the line array speakers with frames in an industry standard transportation type truck, which has about a 96 inch vertical cargo height. Most systems known in the art are designed without the dimensional considerations in mind to ease the actual practice of loading and transporting the systems.
Therefore, a need exists for line array speakers that are easy to assemble, transport, and suspend. In addition, a need exists for a line array system having the ability to adjust and rigidly maintain the curvature of the line array system and the splay angle between adjacent speakers.